A sealing material in a planar type solid oxide fuel cell, being inserted between a interconnector and an electrolyte, is used to separate a fuel gas supplied to an anode of the cell from the air supplied to a cathode of the cell. Currently, various kinds of sealing materials have been developed. Among them, glass-ceramic composite sealants have the best quality in gas tightness. However, it is difficult to carry out a pressurizing operation using a composite sealant composed only of a glass matrix phase.
In order to solve this problem, a stack may be installed in a pressurizing container to operate in a pressurizing operation. In this case, however, the pressurizing container may undesirably increase the bulk of the stack itself and require additional installation cost.
Accordingly, a sealing material is needed which is capable of securing the gas-tightness of the stack without requiring an additional pressurizing container.